The present invention relates to a bonding head for mounting electronic components to a circuit board and, a component mounting apparatus with the bonding head.
Conventionally, a spherical bearing is used as an example of parallel adjustment devices for the aforementioned bonding head. The spherical bearing can adjust parallelism of the bonding head by making a pressing tool of the bonding head follow an object such as a bonding stage or the like, thereby facilitating parallel adjustment.
One example of the bonding heads employing the spherical bearing in a parallel adjustment part will be described below with reference to drawings. FIG. 9 is a perspective view of the conventional bonding head and FIG. 10 is a sectional view of the bonding head. In these FIGS. 9 and 10, a spherical part 2 of a bonding head 1 is constituted so that a block 3 with a convex-shaped spherical part and a block 4 with a concave-shaped spherical part are to be brought in contact with each other. The block 3 is sucked and held to the block 4 by sucking the air to suction grooves 5 through a suction passage 6 formed in the block 4. Also the block 3 is attracted to the block 4 by a magnetic force of magnets 7 fitted to the block 4. To the block 3 is connected a cooling fin 8. A holder 9 coupled to the cooling fin 8 has a pressing tool 10 at a lower end of the holder, to which are inserted a heater 11 and a thermocouple 12 from the same direction. The holder 9 is accordingly heated by the heater 11 while its temperature is monitored by the thermocouple 12. A point xe2x80x9caxe2x80x9d of the center of a lower face of the pressing tool 10 is made the center of a sphere of the spherical part 2. An electronic component 13 is mounted onto a circuit board 15 via a thermosetting adhesive 14. The circuit board 15 is placed on a bonding stage 16.
The bonding head in the above constitution operates as follows.
A bonding operation will be discussed in the first place.
The electronic component 13 is temporarily positioned on the circuit board 15 via the adhesive 14 in a precedent process. The circuit board 15 with the electronic component 13 temporarily positioned thereto is transferred by an outside transfer device not shown in the drawings and fixedly placed on the bonding stage 16. The bonding head 1 is lowered by an external driving device not shown in the drawings thereby pressing the electronic component 13 by the pressing tool 10. Since the pressing tool 10 is heated by the heat of the heater 11 via the holder 9 at this time, the heat of the pressing tool 10 is conducted to the adhesive 14 via the electronic component 13. As a result, setting of the adhesive 14 proceeds to complete joining the electronic component 13 and the circuit board 15. It is important to secure a high parallelism here between the electronic component 13 and the circuit board 15 so as to obtain a high quality of the joining. In other words, a parallelism between the pressing tool 10 and the bonding stage 16 is crucial for high-quality bonding.
An operation of adjusting the parallelism will now be described with reference to FIG. 10. The parallelism adjustment operation is carried out when it becomes necessary to replace the pressing tool 10 according to types of products to be produced. The parallelism adjustment operation is carried out without works, i.e., the electronic component 13 and the circuit board 15 loaded on the bonding stage 16. Although the work is illustrated in FIG. 10, actually no work is present during the parallelism adjustment operation.
Before the parallelism adjustment operation, the air is sucked through the suction passage 6, whereby the block 3 is sucked and held to the block 4 by an air suction force at the suction grooves 5.
In the parallel adjustment operation, a compressed air is first supplied to the suction passage 6 to release the above suction and holding to the block 3, while the block 3 is prevented from dropping because of a force of magnets 7 acting to hold the block 3. Consequently a gap of severalxe2x80x94several tens xcexcm is generated between the block 3 and the block 4 at the spherical part. The block 3 is rendered freely rotatable centering the point xe2x80x9caxe2x80x9d. On the other hand, since the holder 9 has the heater 11 and the thermocouple 12 equipped thereto in the same direction along a direction xe2x80x9cbxe2x80x9d as mentioned before, a turning moment in a direction xe2x80x9ccxe2x80x9d is given rise to the holder 9 by effects of weights of the heater 11 and the thermocouple 12 and drags of wiring lines 17 and 18. A lower part 19 of the bonding head which is made rotatable as above eventually comes to incline as shown in FIG. 11.
Then the bonding head 1 is moved down by the external driving device not shown in the drawings to press the pressing tool 10 to the bonding stage 16. The pressing tool 10 tends to follow the bonding stage 16 at its pressing face, hence rotating the block 3 about the point xe2x80x9caxe2x80x9d. After the rotation, the block 3 is sucked and held to the block 4 through suction of the air from the suction grooves 5.
In the bonding head 1 constituted as above, when the pressing tool 10 is to follow the bonding stage 16, drags of the wiring lines 17 and 18 of the heater 11 and the thermocouple 12 and weights of the heater 11 and the thermocouple 12 adversely effect to generate the drag to hinder the pressing tool from tracing the bonding stage. In consequence of this, a sufficient parallelism of the electronic component 13 to the circuit board 15 cannot be secured in the bonding operation. Thus, a contact state of electrodes between the electronic component 13 and the circuit board 15 varies. High-quality bonding cannot achieve in the conventional art.
The present invention is devised to solve the above problem and has for its object to provide a bonding head in which a pressing face can be arranged to a bonding stage with a higher parallelism than in the conventional art, and a component mounting apparatus with the bonding head.
In order to accomplish the aforementioned objective, according to a first aspect of the present invention, there is provided a bonding head for pressing a component to a circuit form object with a pressing face brought in contact with the component, which comprises:
a pressing part having the flat pressing face which comes in contact with the component on a circuit form object placed on a stage face of a bonding stage;
a supporting part for supporting the pressing part while allowing the pressing part to freely swing; and
an inclination prevention member for preventing the pressing part from inclining to the supporting part in consequence to the swing of the pressing part so as to make the pressing face nearly parallel to the stage face.
As described above, the bonding head of the first aspect of the present invention is provided with the inclination prevention member. The pressing part is prevented by the inclination prevention member from inclining to the supporting part, so that the pressing face is made nearly parallel to the stage face. Therefore the pressing face can be arranged with a higher parallelism to the bonding stage in comparison with the conventional art. Thus components and a circuit form object can be bonded with the high bonding quality.
The above inclination prevention member may be constituted of a heating member for heating the component, which is included in the pressing part, and includes a heating element for heating the pressing face and a heat detector for detecting heat caused by the heating element thereby controlling a temperature of the heating element, to which the heating element and the heat detector are loaded with directions to offset the swing of the pressing part brought about by the heating element and the swing of the pressing part brought about by the heat detector.
The inclination of the pressing part to the supporting part can be prevented by constituting the heating member as the inclination prevention member, the heating member having the heating element and the heat detector attached to the heating member in directions in which the swing of the pressing part by the heating element is offset by the swing of the pressing part by the heat detector. The pressing face and the stage face can accordingly be arranged to be nearly parallel.
In the bonding head, a coating material of wiring lines connected to the heating element and the heat detector can be formed of a material permitting parallel adjustment to the pressing part, the operation making the pressing face and the stage face parallel to each other when the pressing face is brought in contact with the stage face.
The coating material used for the wiring lines connected to the heating element and the heat detector is one that permits the parallel adjustment for the pressing part to make the pressing face and the stage face parallel to each other when the pressing face is brought in contact with the stage face. Accordingly the pressing part can be prevented from inclining to the supporting part and the pressing face and the stage face are brought in the state to be nearly parallel.
The heating member of the bonding head may be formed symmetric with respect to a center axis of the heating member in two mutually orthogonal directions each orthogonal to a thickness direction of the component to be pressed by the pressing face.
When a shape of the heating member is formed in a symmetric shape, the heating member can be balanced in weight, thus preventing the pressing part from inclining to the supporting part to enable the pressing face and the stage face to be arranged nearly in parallel. The pressing face can be disposed to the bonding stage with the higher parallelism as compared with the conventional art.
The above pressing face may be formed to have a size which is larger than an entire face of the component and makes the pressing part generate a rotational force for allowing the pressing face and the stage face to be parallel when the pressing face is brought in contact with the stage face.
The pressing face is formed in the size by which the rotational force for making the pressing face and the stage face be parallel when the pressing face is brought in contact with the stage face is generated to the pressing part. Therefore since the rotational force for making the pressing face and the stage face be in the parallel state is generated when the pressing face is brought in contact with the stage face, the pressing face and the stage face can be easily arranged to be nearly parallel to each other. The pressing face can thus be disposed with the higher parallelism to the bonding stage in comparison with the conventional art.
When the component includes a pressing prohibition portion, the pressing face may be provided with a non-pressing portion corresponding to the pressing prohibition portion.
The non-pressing portion is provided to the pressing face for components including pressing prohibition portions, whereby the components can be mounted without being deteriorated in quality.
The inclination prevention member may be constituted of a weight attached to the pressing part for making the pressing part generate a rotational force for allowing the pressing face and the stage face to be nearly parallel.
By attaching the weight to the pressing part as the inclination prevention member, the weight balance of the pressing part can be obtained, so that the pressing part is prevented from inclining to the supporting part and the pressing face can be arranged to be nearly parallel to the stage face. The pressing face can be arranged with the higher parallelism to the bonding stage in comparison with the conventional art.
Furthermore, the inclination prevention member can be constituted of an urging mechanism attached to the supporting part for applying to the pressing part a rotational force for allowing the pressing face and the stage face to be nearly parallel.
With the urging mechanism being attached as the inclination prevention member to the supporting part, the rotational force for making the pressing face and the stage face be nearly parallel can be applied to the pressing part, whereby the pressing part is prevented from inclining to the supporting part and the pressing face can be arranged in nearly parallel state to the stage face. The pressing face can be arranged with the higher parallelism to, the bonding stage than in the conventional art.
When the heating member further includes a suction passage opened to the pressing face for sucking the component to the pressing face, the inclination prevention member can be a tubular member which is attached to the heating member, communicates with the suction passage and is formed of a material or in a size to prevent the inclination.
When the pressing part is equipped with the suction passage for sucking the component, the material of the tube communicating with the suction passage, as the inclination prevention member, is formed of material or size in which the inclination of the pressing part to the supporting part is prevented. The pressing face and the stage face can be set nearly parallel to each other, and the pressing face can be arranged with the higher parallelism to the bonding stage as compared with the conventional art.
A component mounting apparatus is provided according to a second aspect of the present invention which comprises:
a bonding head of the first aspect; and
a transfer device for feeding the circuit form object with the component placed thereon onto the stage face of the bonding stage and sending out the circuit form object from the stage face,
wherein the component on the circuit form object fed onto the stage face by the transfer device is mounted on the circuit form object while pressing by the bonding head.
The component mounting apparatus according to the second aspect of the present invention has the bonding head of the above first aspect. Since the pressing face can be arranged with the higher parallelism to the bonding stage than in the conventional art, components and a circuit form object can be bonded with the higher bonding quality.
In the above second aspect may be also included a driving device for moving the bonding head in a thickness direction of the component and a controller for controlling the driving device to operate, wherein the controller controls the driving device to move the bonding head in the thickness direction with a larger force at a parallel adjustment operation when a flat pressing face which is to come in contact with the component is brought in contact with the stage face to make the pressing face and the stage face parallel than a force at a pressing operation when the pressing face is brought in contact with the component to press the component to the circuit form object.
The component mounting apparatus of the second aspect further includes the controller for controlling to press the pressing face with a larger force to the stage face at the parallel adjustment than a force of the component to the circuit form object. Therefore, the pressing face is more easily arranged in the parallel state to the stage face, enabling bonding the components and circuit form object with the higher bonding quality.